Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Matrícula que tem uma escola do sul central (union mills) tem qual soma?
 ###Tabelas: CREATE TABLE season_5_1992 (season_5_1992_id AUTO_INCREMENT PRIMARY KEY, Number in series INT, Number in season INT, Title VARCHAR, Directed by VARCHAR, Original air date VARCHAR, Production code VARCHAR) CREATE TABLE series_ratings (series_ratings_id AUTO_INCREMENT PRIMARY KEY, Season INT, # of Episodes INT, Timeslot VARCHAR, Season Premiere VARCHAR, Season Final VARCHAR, Peak Audience INT, Average Audience INT, Average Nightly Rank VARCHAR, Average Weekly Rank VARCHAR, Average Yearly Ranking VARCHAR) CREATE TABLE transfers (transfers_id AUTO_INCREMENT PRIMARY KEY, 1 January 2010 VARCHAR, DF VARCHAR, Adam Hinshelwood VARCHAR, Aldershot Town VARCHAR, Wycombe Wanderers VARCHAR, Undisclosed VARCHAR) CREATE TABLE 1900-1912 (1900-1912_id AUTO_INCREMENT PRIMARY KEY, Average population (x 1,000) INT, Live births INT, Deaths INT, Natural change INT, Crude birth rate (per 1,000) INT, Crude death rate (per 1,000) INT, Natural change (per 1,000) INT) CREATE TABLE  (_id AUTO_INCREMENT PRIMARY KEY, School VARCHAR, City VARCHAR, Mascot VARCHAR, Enrollment INT, County VARCHAR)  
SELECT SUM Enrollment FROM  WHERE School = south central (union mills)